There are many hydrocarbon producing wells which are incapable of sustaining a velocity within the production tubing which is in excess of the critical flow rate of the well. Hence the velocity is insufficient to prevent generation of a liquid column or hydrostatic head which accumulates within the production tubing and eventually loads up the well. These wells usually are referred to as low-volume gas wells or high GOR (gas-oil ratio) oil wells. In such an instance, liquid progressively accumulates within the production string, and eventually the accumulated hydrostatic head will attain a value which essentially "shuts in" or kills the well.
A well that loads up with liquid can be pulse flowed by charging the borehole annulus with compressed gaseous fluid, such as natural gas, whereupon the production string can then be opened to the production outflow line, and the liquid slug expelled from the bottom extremity of the borehole. Of course, the pressure of the added gaseous product must be of a magnitude to produce a flow rate of a velocity which will unload the accumulated liquid slug from the well tubing.
Generally, wells of this nature are operated on a time cycle and must rely upon pressure being effected each cycle within the entire tubing string and annulus in order to unload a logged-in or dead well. This expedient is time consuming and wasteful of gas, as well as periodically causing the outflow line to be momentarily overloaded. Accordingly, this undesirable solution also causes other problems, such as difficulty in correctly attaining proper gas measurements at the meter run, and interference with the operation of other downstream equipment and apparatus.
Accordingly, it is desirable to have made available a system and method of subsurface well control and operation which is responsive to changes in both surface and subsurface pressures, and which employs a minimum producing flowing bottomhole pressure, so that an optimum amount of gas and liquid is automatically produced from the well bore.